Microsoft Security Bulletin MS13-045 - Important

General Information

Executive Summary

This security update resolves a privately reported vulnerability in Windows Essentials. The vulnerability could allow information disclosure if a user opens Windows Writer using a specially crafted URL. An attacker who successfully exploited the vulnerability could override Windows Writer proxy settings and overwrite files accessible to the user on the target system. In a web-based attack scenario, a website could contain a specially crafted link that is used to exploit this vulnerability. An attacker would have to convince users to visit the website and open the specially crafted link.

This security update is rated Important for Windows Writer when installed on all supported editions of Microsoft Windows. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by correcting the way Windows Writer handles URL parameters. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

Recommendation. Microsoft recommends that customers apply the update at the earliest opportunity.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

Knowledge Base Article

Affected and Non-Affected Software

The following software have been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.

[1]There is no update available for Windows Essentials 2011. See update FAQ for details.
[2]This update is available for download only.
Update FAQ
----------
**Where is the update for Windows Essentials 2011?**
There is no update available for Windows Essentials 2011 because Microsoft recommends that all customers using this version upgrade to Windows Essentials 2012. Windows Essentials 2012 is available from the [Windows Essentials](http://get.live.com/) download page.
**What can I do if I cannot upgrade my version of Windows Essentials?**
Customers who cannot upgrade their version of Windows Essentials can disable the Windows Writer handler. For more information on how to disable the Windows Writer handler, see the workaround in the **Windows Essentials Improper URI Handling Vulnerability - CVE-2013-0096** section.
**I am using an older release of the software discussed in this security bulletin. What should I do?**
The affected software listed in this bulletin have been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, see the [Microsoft Support Lifecycle](http://go.microsoft.com/fwlink/?linkid=21742) website.
It should be a priority for customers who have older releases of the software to migrate to supported releases to prevent potential exposure to vulnerabilities. To determine the support lifecycle for your software release, see [Select a Product for Lifecycle Information](http://go.microsoft.com/fwlink/?linkid=169555). For more information about service packs for these software releases, see [Service Pack Lifecycle Support Policy](http://go.microsoft.com/fwlink/?linkid=89213).
Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, see the [Microsoft Worldwide Information](http://go.microsoft.com/fwlink/?linkid=33329) website, select the country in the Contact Information list, and then click **Go** to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the [Microsoft Support Lifecycle Policy FAQ](http://go.microsoft.com/fwlink/?linkid=169557).
### **Vulnerability Information**
Severity Ratings and Vulnerability Identifiers
----------------------------------------------
The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the [May bulletin summary](http://technet.microsoft.com/security/bulletin/ms13-may). For more information, see [Microsoft Exploitability Index](http://technet.microsoft.com/security/cc998259).

Windows Essentials Improper URI Handling Vulnerability - CVE-2013-0096
----------------------------------------------------------------------
An information disclosure vulnerability exists when Windows Writer fails to properly handle a specially crafted URL. An attacker who successfully exploited the vulnerability could override Windows Writer proxy settings and overwrite files accessible to the user on the target system.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see [CVE-2013-0096](http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=cve-2013-0096).
#### Mitigating Factors
Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:
- In a web-based attack scenario, an attacker would have to host a website and convince a user to click on a specially crafted URL in order to exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these websites. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes users to the attacker's website.
#### Workarounds
Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:
- **Apply the Microsoft Fix it solution, "Disable the Windows Writer" that prevents exploitation of this vulnerability**
See [Microsoft Knowledge Base Article 2813707](http://support.microsoft.com/kb/2813707) to use the automated **Microsoft Fix it** solution to enable or disable this workaround.
**Impact of workaround.** Users who have configured their systems with this workaround will be unable to process Windows Writer handler requests that would normally launch Windows Writer.
#### FAQ
**What is the scope of the vulnerability?**
This is an information disclosure vulnerability.
**What causes the vulnerability?**
The vulnerability is caused when Windows Writer fails to properly handle URL parameters.
**What is Windows Essentials?**
Windows Essentials is a suite of products available in one easy download. The suite includes Photo Gallery, Mail, Movie Maker, Writer, Family Safety, Bing Bar, and Microsoft Silverlight.
**What is Windows Writer?**
Windows Writer is a client application for Windows that provides users with a way to create, update, and manage blog content online. The application is part of the free Windows Essentials software suite, which includes several applications (such as Messenger, Mail, Photo Gallery, and Movie Maker) that perform common tasks in the consumer space.
**What might an attacker use the vulnerability to do?**
An attacker who successfully exploited this vulnerability could override Windows Writer proxy settings and overwrite files accessible to the user on the target system.
**How could an attacker exploit the vulnerability?**
For this vulnerability to be exploited a user must open Writer using a specially crafted URL.
In an email attack scenario, an attacker could exploit the vulnerability by sending an email message containing the specially crafted URL to a user and by convincing the user to click the specially crafted URL.
In a web-based attack scenario, an attacker would have to host a website that contains a specially crafted URL. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted website. Instead, an attacker would have to convince them to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes them to the attacker's website, and then convince them to click on the specially crafted URL.
**What systems are primarily at risk from the vulnerability?**
Systems with Windows Writer installed are at risk.
**What does the update do?**
The update addresses the vulnerability by correcting the way Windows Writer handles URL parameters.
**When this security bulletin was issued, had this vulnerability been publicly disclosed?**
No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.
**When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?**
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
### Update Information
Detection and Deployment Tools and Guidance
-------------------------------------------
**Security Central**
Manage the software and security updates you need to deploy to the servers, desktop, and mobile systems in your organization. For more information see the [TechNet Update Management Center](http://go.microsoft.com/fwlink/?linkid=69903). The [Microsoft TechNet Security website](http://go.microsoft.com/fwlink/?linkid=21132) provides additional information about security in Microsoft products.
Windows Essentials 2012 is available from the [Windows Essentials](http://get.live.com/) download page.
Security Update Deployment
--------------------------
**Affected Software**
For information about the specific security update for your affected software, click the appropriate link:
#### Windows Essentials 2012
**Reference Table**
The following table contains the security update information for this software.

Security update file name

Windows Essentials 2012:wlsetup-all.exe

Installation switches

Not applicable

Restart Requirement

This update does not require a restart. However, if required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.

Note A registry key does not exist to validate the presence of this update.

### Other Information
#### Acknowledgments
Microsoft [thanks](http://go.microsoft.com/fwlink/?linkid=21127) the following for working with us to help protect customers:
- Andrea Micalizzi, working with Beyond Security's [SecuriTeam Secure Disclosure](http://www.beyondsecurity.com/ssd.html) team, for reporting the Windows Essentials Improper URI Handling Vulnerability (CVE-2013-0096)
#### Microsoft Active Protections Program (MAPP)
To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please go to the active protections websites provided by program partners, listed in [Microsoft Active Protections Program (MAPP) Partners](http://go.microsoft.com/fwlink/?linkid=215201).
#### Support
**How to obtain help and support for this security update**
- Help installing updates: [Support for Microsoft Update](http://support.microsoft.com/ph/6527)
- Security solutions for IT professionals: [TechNet Security Troubleshooting and Support](http://technet.microsoft.com/security/bb980617.aspx)
- Help protect your computer that is running Windows from viruses and malware: [Virus Solution and Security Center](http://support.microsoft.com/contactus/cu_sc_virsec_master)
- Local support according to your country: [International Support](http://support.microsoft.com/common/international.aspx)
#### Disclaimer
The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
#### Revisions
- V1.0 (May 14, 2013): Bulletin published.
- V1.1 (May 15, 2013): Corrected link to the download location in the Detection and Deployment Tools and Guidance section. This is an informational change only.
*Built at 2014-04-18T13:49:36Z-07:00*